HELICOBACTER-PYLORI EXPRESSES A COMPLEX SURFACE CARBOHYDRATE, LEWIS-X

Monoclonal antibodies (MAbs) specific for Lewis X (Le(x)) reacted with whole cells of Helicobacter pylori NCTC11637, UA799, UA802, UA825, UA 861., UA1182, and UA1206 in immunoelectron microscopy and enzyme-linke d immunosorbent assay (ELISA) experiments, These MAbs have documented specificity to Le(x), whereas MAbs for Le(a) and Le(b) were negative i n both immunoelectron microscopy and ELISA. H. pylori coccoid forms al so reacted with the MAbs, whereas the flagellum lacking the sheath sho wed no reactivity, The Le(x) structures were associated with membrane fractions in the ELISA experiments, and silver-stained sodium dodecyl sulfate-polyacrylamide gels confirmed the presence of lipopolysacchari des which reacted with the MAbs in immunoblots, Serum from an H. pylor i-infected individual contained immunoglobulins which blocked the bind ing of the Le(x) MAbs, indicating that part of the host immune respons e to H. pylori is to the Le(x) structure, The ability of this gastric pathogen to mimic an oncofetal antigen (self) could explain the down r egulation of anti-H. pylori T-cell response seen in H. pylori-infected individuals.